3.18-stable patches

3.18-stable patches

added patches:
	groups-consolidate-the-setgroups-permission-checks.patch
	mnt-implicitly-add-mnt_nodev-on-remount-when-it-was-implicitly-added-by-mount.patch
	mnt-update-unprivileged-remount-test.patch
	umount-disallow-unprivileged-mount-force.patch
	userns-add-a-knob-to-disable-setgroups-on-a-per-user-namespace-basis.patch
	userns-allow-setting-gid_maps-without-privilege-when-setgroups-is-disabled.patch
	userns-check-euid-no-fsuid-when-establishing-an-unprivileged-uid-mapping.patch
	userns-document-what-the-invariant-required-for-safe-unprivileged-mappings.patch
	userns-don-t-allow-setgroups-until-a-gid-mapping-has-been-setablished.patch
	userns-don-t-allow-unprivileged-creation-of-gid-mappings.patch
	userns-only-allow-the-creator-of-the-userns-unprivileged-mappings.patch
	userns-rename-id_map_mutex-to-userns_state_mutex.patch